Unitus DSpacehttp://http://dspace.unitus.it:80
The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Sat, 10 Dec 2016 01:09:21 GMT2016-12-10T01:09:21ZElectronic nose and SPME techniques to monitor phenanthrene biodegradation in soilhttp://hdl.handle.net/2067/1870
Title: Electronic nose and SPME techniques to monitor phenanthrene biodegradation in soil
Authors: De Cesare, Fabrizio; Pantalei, Simone; Zampetti, Emiliano; Macagnano, Antonella
Abstract: In this work two recently developed techniques (solid phase microextraction-SPME associated to gas-chromatography mass spectrometry-GC/MS analysis and electronic nose-EN), able to analyse the headspace of solid or liquid samples, were used to monitor the possible degradation of phenanthrene in an artificially contaminated soil. The analysis by SPME-GC/MS showed a drastic decrease of phenanthrene content after 30 days of incubation (-92%) and different treatments with nutritive solutions and/or surfactant improve this rate up to 97%. Differently, the analysis of soil headspaces by EN, processed by principal component analysis (PCA), showed that both contaminated and uncontaminated soil samples (controls) might be distinguished on a temporal scale and that they were delayed relative to controls. The application of PLS-DA to chromatograms obtained by SPME-GC/MS pointed out the presence, in polluted soils, of a series of possible indicators involved in the phenanthrene degradation, which were completely absent in relative control sample.; In questo lavoro, due tecniche sviluppate recentemente (la microestrazione in fase solida-SPME abbinata alla gascromatografia e all’analisi della massa molecolare-GC/MS e il naso elettronico-EN) capaci di analizzare lo spazio di testa di campioni solidi o liquidi sono stati usati per minitorare la possibile degradazione del fenantrene in suoli contaminati artificialmente. L’analisi tramite SPME-GC/MS ha mostrato una drastica diminuzione del contenuto di fenantrene dopo 30 giorni di incubazione (-92%) e l’applicazione di trattamenti con soluzioni nutritive e/o surfattanti hanno migliorato tale tasso di diminuzione fino al 97%. Differentemente, l’analisi dello spazio di testa tramite l’EN, processata tramite PCA, ha mostrato che sia i campioni contaminati che quelli non contaminati (controlli) potevano essere distinti su scala temporale ed inoltre la presenza di un ritardo nell’evoluzione degli ecosistemi contaminati con fenantrene rispetto a quanto osservabile nei controlli. L’applicazione della PLS-DA ai cromatogrammi ottenuti tramite SPME-GC/MS ha evidenziato la presenza, nei suoli contaminati, di una serie di possibili indicatori coinvolti nella degradazione del fenantrene che erano completamente assenti nei relativi campioni di controllo.
Description: L'articolo è disponibile sul sito dell'editore: http://www.sciencedirect.comMon, 31 Dec 2007 23:00:00 GMThttp://hdl.handle.net/2067/18702007-12-31T23:00:00ZUse of electronic nose technology to measure soil microbial activity through biogenic volatile organic compounds and gases releasehttp://hdl.handle.net/2067/2375
Title: Use of electronic nose technology to measure soil microbial activity through biogenic volatile organic compounds and gases release
Authors: De Cesare, Fabrizio; Di Mattia, Elena; Pantalei, Simone; Zampetti, Emiliano; Vinciguerra, VIttorio; Canganella, Francesco; Macagnano, Antonella
Abstract: Gas and volatile organic compounds (VOCs) release in soil is known to be linked to microbial activity and can differently affect the life of organisms in soil. Electronic noses (E-noses) are sensing devices composed of sensor arrays able to measure and monitor gases and VOCs in air. This is the first report on the use of such a sensing device to measure specifically microbial activity in soil. In the present study, γ-irradiated sterilised soil was inoculated with Pseudomonas fluorescens. To be sure for a rapid microbial growth and activity, two pulses of nutrient solution with organic and inorganic C, N, P and S sources were added to soil and the resulting microcosms were incubated for 23 d. During the incubation, respiration and enzyme activities of acid phosphatase, β-glucosidase, fluorescein diacetate hydrolase and protease, were measured, and microbial growth as global biomass of vital cells based on substrate-induced respiration (SIR-Cmic) and enumeration of viable and culturable cells by means of dilution plate counts (CFU) were also monitored. Concurrently, VOCs and/or gas evolution in the headspace of the soil microcosms were measured through the E-nose, upon their adsorption on quartz crystal microbalances (QCMs) comprising the sensory device. The E-nose typically generated an odorant image (olfactory fingerprint) representative of the analysed samples (soils) and resulting from the concurrent perception of all or most of the analytes in headspace, as it commonly happens when several selective but not specific sensors are used together (array). The basic hypothesis of this study was that different soil ecosystems expressing distinct microbial metabolic activities, tested through respiration and enzyme activities, might generate different olfactory fingerprints in headspace. Furthermore, the possibility to detect several substances at the same time, released from the soil ecosystems, possibly deriving from both abiotic and biotic (microbial metabolism) processes provides an “odorant image” representative of the whole ecosystem under study. The E-nose here used succeeded in discriminating between inoculated and non-inoculated ecosystems and in distinguishing different metabolic and growth phases of the inoculated bacteria during incubation. Specifically, E-nose responses were proved highly and significantly correlated with all hydrolytic activities linked to the mobilisation of nutrients from soil organic matter and their cycling, with CO2 fluxes (respiration and presumed heterotrophic fixation) and with P. fluorescens population dynamics during exponential, stationary and starvation phases measured by SIR-Cmic and CFUs. Interestingly, the E-nose successfully detected soil microbial activity stimulated by nutrient supply, even though none of the catalytic activities tested directly produced VOCs and/or gases. The E-nose technology was then proved able to supply a real holistic image of microbial activity in the entire gnotobiotic and axenic soil ecosystems.Fri, 31 Dec 2010 23:00:00 GMThttp://hdl.handle.net/2067/23752010-12-31T23:00:00ZBiomimetic sensing layer based on electrospun conductive polymer webshttp://hdl.handle.net/2067/2373
Title: Biomimetic sensing layer based on electrospun conductive polymer webs
Authors: Zampetti, Emiliano; Pantalei, Simone; Scalese, Silvia; Bearzotti, Andrea; De Cesare, Fabrizio; Spinella, Corrado; Macagnano, Antonella
Abstract: The aim of the present study is to combine a bio-inspired nanofibrous artificial epithelium to the electronic nose (e-nose) principles. The sensing device set up was an electronic nose consisting of an array of 9 micro-chemoresistors (Cr–Au, 3 × 3) coated with electrospun nanofibrous structures. These were comprised of doped polyemeraldine base blended with 3 different polymers: polyethylene oxide, polyvinilpyrrolidone and polystyrene, which acted as carriers for the conducting polymer and were the major responsible of the features of each fibrous overlay (electrical parameters, selectivity and sensitivity ranges). The two sensing strategies here adopted and compared consisted in the use of 2 different textural coatings: a single- and a double-overlay, where the double-overlay resulting from overdeposition of 2 different polymer blends. Such e-nose included a plurality of nanofibres whose electrical parameters were at the same time depending on each polymer exposure to analytes (NO2, NH3) and on the spatial distribution of the interlacing fibres. The morphology of the coating arrangements of this novel e-nose was investigated by scanning electron microscopy (SEM) and its sensor responses were processed by multicomponent data analyses (PCA and PLS) reporting encouraging results for detection and recognition of analytes at ppb levels.Fri, 31 Dec 2010 23:00:00 GMThttp://hdl.handle.net/2067/23732010-12-31T23:00:00ZComparison between sensing systems for ammonium detection and measurement in soilhttp://hdl.handle.net/2067/2369
Title: Comparison between sensing systems for ammonium detection and measurement in soil
Authors: De Cesare, Fabrizio; Zampetti, Emiliano; Pantalei, Simone; Macagnano, Antonella
Abstract: Usually, ammonium in soil is carried out through steam distillation of ammonia obtained after alkalinization of soil extracts and further back titration of the collected solutions. Alternatively, ion selective electrodes (ISE) specific for ammonium ions can be used, in order to measure their concentration in aqueous soil extracts. The aim of this study is to assess the possibility to use, alternatively to the previous techniques, two kinds of chemical sensors able to measure NH3, such as an interdigital microelectrode (IDE) coated of conductive polymer and a sensors array, usually named electronic nose (EN), based on quartz crystal microbalances (QCMs) covered with functionalized polymers. These sensors were chosen on the base of their ability to detect NH3 in sample headspace (specifically or aspecifically, respectively). Therefore, NH4+ in solution was converted to NH3 by alkalinizing soil extracts. Sensors were calibrated at first against known concentrations of NH4+. Results were compared with those obtained with an ISE for NH4+.Wed, 31 Dec 2008 23:00:00 GMThttp://hdl.handle.net/2067/23692008-12-31T23:00:00Z